It has long been known in the field of archery, bow hunting, target shooting, and the like that use of an archery arrow that is warped or imbalanced can seriously affect a shooter's accuracy, even if a shot is executed properly. It is therefore highly desirable, particularly when hunting or competing with a bow and arrow, that each arrow used be straight and balanced, or, in other words, that the arrows be true.
Various methods and devices have been used by archers in the past for determining whether or not their arrows are true. In some cases, the archer simply spins the arrow between the palms of his hands and attempts to "feel" any imperfections in the arrow. Archers have also been known to balance an arrow in the palm of a hand and manually spin the arrow while balanced, again in an attempt to "feel" perturbations in the arrow's spin that would indicate a defect. Each of these methods must sometimes be relied upon, particularly when an archer is in the filed without access to more sophisticated equipment. However, they tend to be highly insensitive to all but the grossest imperfections in the arrow and thus give only a rough indication of the arrow's condition.
More sophisticated methods and devices for determining the trueness of an archery arrow have also been developed. These include the arrow straightness gauge disclosed in U.S. Pat. No. 4,155,172 of Bartol. The gauge comprises an elongated rigid rod having a longitudinal bore extending therethrough. The bore has a diameter slightly larger than the diameter of the shaft of an arrow to be tested. In use, an arrow is simply inserted through the longitudinal bore. If the arrow fits freely in the bore, then it is straight within the tolerances of the bore. If it becomes jammed in the bore, then it is unacceptably warped.
The Bartol device is a step in the right direction but nevertheless is lacking in many important respects. For example, the device is limited in accuracy because of restrictions on the size of the bore imposed by slightly different arrow shaft diameters from one brand to another or even within brands. Furthermore, the Bartol device only provides for a check of an arrow's straightness and gives no indication of whether the arrow is balanced or imbalanced, which is also an important factor in assuring shooting accuracy.
Another previous device for checking the trueness of arrows is disclosed in U.S. Pat. No. 5,121,549 of Gudausky. In this device, an arrow is laid horizontally between spaced stands with the arrow shaft being supported between pairs of rotatable disks mounted in each stand. The arrow can then be rotated while supported on the disks so that imperfections in the arrow can be observed.
Like the Bartol device, Gudausky, while somewhat useful, is nevertheless plagued with various inherent shortcomings that can render it less than satisfactory. For instance, the device is highly dependent on the absolute accuracy with which the rotating disks are formed since even a slightly out-of-round or off-centered disk would falsely indicate a defect in the arrow. Further, the Gudausky device, like Bartol, provides an indication only of straightness and not of balance. This is because the weight of the arrow must at all times remain supported by the disks so that rotational perturbations that might be caused by imbalance as the arrow spins are damped out and not observable. Thus, Gudausky, too, falls short of the mark.
Accordingly, there exists a persistent and heretofore only partially addressed need for a reliable, simple, inexpensive, and accurate method and device for determining quickly both the straightness and balance of an archery arrow. It is to the provision of just such a method and apparatus that the present invention is primarily directed.